1. Field of the Invention
This invention relates generally to the field of fabrics and other sheet-type materials, and more particularly to such sheet materials used as window coverings and which may be incorporated in window covering structures.
2. Description of the Prior Art
The window shade industry has developed many methods and apparatus for covering windows that provide privacy and thermal insulation while being aesthetically pleasing. Such window coverings should be capable of being raised and lowered as access to the window and other factors dictate. It would be advantageous to provide a venetian-type window covering that could, without being raised or lowered, be selectively placed in a closed position that provides privacy and insulation. The window covering should also be capable of being moved into an open position, allowing light and air to pass through the window covering.
One attempt to provide such a window covering is disclosed in U.S. Pat. No. Reissue 30,254 to Rasmussen. Rasmussen shows a honeycomb curtain structure that operates as a venetian-type window cover. Rasmussen accomplished this by forming a curtain structure from a series of foldable cells adhered together. Each cell has opposed side portions and a connected part. Thus, when the cells are connected, one series of connected side portions form a front of the curtain structure and the opposite series of connected side portions form a back of the structure. The structure of Rasmussen also has a series of connecting parts being parallel to and spaced apart from one another located between the front and back of the curtain. In this configuration, the curtain may either be rolled-up on a roller or lifted with cords running between the front and back portions and through the connecting parts.
Another attempt to provide such a venetian-type window covering is disclosed in U.S. Pat. No. 3,384,591 to Froget. Froget shows a composite cloth which may be used as a blind. When the cloth is used as a blind, it is comprised of two transparent sheets connected by movable and opaque blades which are parallel to one another and are regularly separated and welded to the sheets. When the opaque blades of Froget are vertically aligned so as to prevent light from passing through the structure, the composite cloth structure is flat and has no cellular or honeycomb configuration.
U.S. Pat. No. 5,103,469 to Colson shows a method of making a roman shade. In his roman shade construction, Colson creases two sheets of material and then joins the two sheets of material together in the area of confronting creases of two sheets. Colson shows the two sheets being connected directly to one another or indirectly through a separate connecting member by a bead of adhesive. Colson explains that this adhesive may extend along the full length of the crease or may be applied intermittently. In each of the embodiments of Colson, either the opposed creases or the creases in the connecting member are overlappingly adhered to one another through the bead of adhesive. Thus, the adhesive creates a flat surface bond between fabrics.
The most difficult aspects of bonding thin edges of fabric together or to a crease in fabric is to accurately locate and hold the fabric members in the precise location then deliver a very small amount of adhesive, typically only a few thousandths of an inch thick, over relatively long length and simultaneously clamping everything together.
In each of the above-referenced U.S. applications, there is difficulty in placing holes for the lift cords through such structures. Furthermore, the adhesive used by Colson, since it is in the form of an adhesive bead, offers little flexure in the structure.